The present invention relates to satellite communications systems. More particularly, the present invention relates to satellite communications systems providing Internet service to computer users.
Computer networking is rapidly becoming ubiquitous in present day society. Computer networks have grown from isolated connections among research scientists and universities to the xe2x80x9cinformation superhighwayxe2x80x9d of today. Access to this superhighway is typically accomplished through the xe2x80x9cInternetxe2x80x9d. The Internet utilizes a transmission control protocol/Internet protocol TCP/IP) communications system which is utilized by hundreds of millions of users worldwide.
Through the use of standardized formats, computer users can easily access and navigate through the abundance of information which is accessible through the Internet. This information includes not only research and news information but has now spread to commercial advertising and business communications which permit users to download images, video, sound clips and/or text documents relating to a company""s products. This information is transmitted over the Internet in measurements commonly referred to as bits.
Conventionally, access to the Internet is achieved by using slow, terrestrial dial-up modems through commercial telephone systems such as the public system telephone network (PSTN). Unfortunately, the fastest transmission rate commonly available over the PSTN is 56 K bits per second (bps). Because such transmission rates are prohibitively slow for some practices, such as the transmission of video information, additional systems have been devised including Integrated Services Digital Network (ISDN) and T1 systems which require special cabling to be constructed to the computer user. Unfortunately, ISDN and T1 communications systems are too expensive for the average computer user. Because it will take a long time and substantial expense to connect computer users to the Internet via highspeed transmission lines, such as fiber optic lines, it is desirable to implement some type of highspeed Internet communications system that could be rapidly and inexpensively implemented. Moreover, as explained above, the Internet is largely accessed through telephone lines and dedicated communication lines. Such infrastructure exists today only in developed countries. In undeveloped countries, communities separated by vast distances have limited telephone service, if any. Even where there is telephone service, the quality of the telephone connection is often poorly suited to support the transmission of digital data at a useable rate.
The lack of access to the Internet is rapidly becoming more of a problem as users have expanded beyond academics, researchers and computer enthusiasts and it has become virtually mandatory for members of the general public to participate in the global community via the Internet. For example, physicians in developed countries now confer electronically over the Internet. School children search encyclopedias, obtain information from far away places and even xe2x80x9cchatxe2x80x9d with other children around the country. Those without access to the Internet are left educationally behind.
To overcome the deficiencies of the present Internet infrastructure, systems have been proposed which make use of satellite communications to access the Internet. For example, Direct TV, a subsidiary of Hughes Electronics, Inc., provides highspeed Internet access through their collection of Direct Broadcast System (DBS) satellites which were originally constructed to provide satellite television service. Unfortunately, the Direct TV system does not provide a communication link for the user to send information back to the Internet via the satellite. Accordingly, a computer user must utilize a separate terrestrial telephone line through the PSTN system or the like to provide communications to an Internet provider. Though the transmission rate from the computer user through the PSTN system to an Internet provider is substantially slower than the downlink from the DBS satellite, this system is generally acceptable as computer users generally receive (download) much greater amounts of data from the Internet than they transmit. Accordingly, it is generally acceptable for the computer user""s uplink (transmission) rate to be substantially less than the computer user""s download rate. However, the Direct TV system suffers from several disadvantages as a user must have both a satellite receiver and a connection to telephone service. In many portions of the globe, access to both a satellite dish and telephone line are unavailable.
In order to overcome this disadvantage, systems have been proposed which utilize a single satellite system for both the uplink and downlink of Internet data to a computer user. For example, an Iridium/Motorola cellular telephone system provides two-way Internet access at approximately 2.4 K bps. Meanwhile, Inmersat has proposed a satellite cellular telephone system which will provide 64 K bps of Internet access. Similarly, U.S. Pat. No. 5,912,883 issued to Herschberg as the inventor and assigned to WorldCom Systems, Inc., discloses a satellite communication system which optimally would permit 9.6 K bps of Internet access. Unfortunately, these rates for transmission and receipt of data to the Internet are far too slow to be practical for many computer users. For example, the transmission of a few seconds of live action video would take literally hours to be transmitted from the Internet over these satellite systems.
Accordingly, there is a substantial need for a lowcost, highspeed system which provides access for the computer user to the Internet.
It would also be desirable if an Internet communication system were provided which could substantially utilize existing communications infrastructure.
Moreover, it would be particularly desirable to provide a communications system which could access the Internet which did not require the utilization of telephone lines or highspeed transmission cables. To this end, it would be even more desirable if the communication system provided the computer user with mobile access to the Internet and/or access to the Internet from remote areas around the world.
Briefly, in accordance with the invention, I provide an improved apparatus and method for providing communications to a computer user or the like. More particularly, my invention is a hybrid satellite communications system which is particularly suitable for providing Internet access to a computer user. The hybrid satellite communications system includes one or more satellites, one or more terrestrial communication stations and a plurality of user units. The one or more satellites act as relay stations and include a first transceiver for receiving and transmitting a first set of RF signals in a first frequency band and a second transceiver for receiving and transmitting a second set of RF signals in a second frequency band. Preferably, the first frequency band is at a significantly higher frequency than the second frequency band.
In operation, the user units, typically including personal computers, transmit signals in the second frequency band to the orbiting satellite system. The second signals are then relayed by the satellite system back to terrestrial ground stations which are connected to an Internet provider by the PSTN system or the like. In this manner, a user""s computer can access, send data or information to the Internet, via the second set of signals passing through the satellite system. In reverse manner, data from the Internet is transmitted to a computer user. The Internet Service Provider is connected to a terrestrial ground station which transmits the Internet data in the form of the first set of signals to the satellite system. The satellite system relays the first set of signals back to the computer user enabling the computer user to decode the Internet information to download images, video, sound clips, business advertising or the like. For purposes herein, the first set of signals will be referred to as xe2x80x9cdownlink signalsxe2x80x9d as they refer to the signals which are downlinked from the satellite to a computer user. Similarly, the second set of signals will be referred to herein as xe2x80x9cuplink signalsxe2x80x9d as they refer to the signals which are transmitted from the computer user.
As stated above, the transmission rate from the user""s computer through the satellite system to the Internet Service Provider is slower than the transmission rate of information provided from the Internet provider to the computer user. This is generally acceptable as computer users typically need to download much larger amounts of data from the Internet than they send.
In a preferred embodiment, the hybrid satellite communications system of the present invention transmits the downlink signal from the satellite system to the user""s computer in X band and/or K band. More preferably, the hybrid satellite communications system uses a standard Ku band Direct Broadcast System (DBS) satellite to send the downlink signals from the Internet Service Provider to the computer user. DBS refers to satellite transmission of signals dedicated by the U.S. Federal Communications Commission in the electromagnetic spectrum from 12.2 GHz to 12.7 GHz for DBS broadcasting. This frequency band has been reserved primarily for the transmission of television signals. Meanwhile, it is preferred that the uplink signals from the user""s computer to the Internet Service Provider be relayed by a Mobile Satellite System (MSS) satellite operating in L-band or S-band or both. More particularly, it is preferred that the return link be limited to the frequency band dedicated for mobile satellite communications between 1.0 GHz and 3.0 GHz, though between 1.9 GHz and 2.2 GHz is even more preferable.
In additional preferred embodiments, the hybrid satellite communication system includes at least two satellites, preferably a DBS satellite and an MSS satellite. A first satellite is provided for receiving and transmitting the downlink signals at the higher frequency band from the Internet Service Provider through the first satellite to the user""s computer, while a second satellite is provided for receiving and transmitting the uplink signals at a much lower frequency band from the user""s computer to the Internet service provider. As would be understood by those skilled in the art, one or more ground stations would typically be provided for relaying data between the first and second satellites and the Internet Service Provider.
In still an additional preferred embodiment, the hybrid satellite communications system includes a plurality of terrestrial nodes which cooperate with the second transceiver, which relays the uplink signals, to offload communications between the user""s computer and the second transceiver. More particularly, the terrestrial nodes operate in similar manner to the second transceiver, such as an MSS satellite, and terrestrial communications system in that they relay uplink signals including Internet information from the user""s computer to the Internet Service Provider. Depending on the number of computer user""s on the system, atmospheric conditions, etc., instead of utilizing a second satellite for receiving the uplink signals from the computer user, the computer user transmits the uplink signals to terrestrial nodes which relays any Internet inquiries, information or data to the Internet Service Provider. In a preferred embodiment, the terrestrial nodes utilize a standard cellular telephone communication system which is connected to an Internet Service Provider by the PSTN. For example, where the computer user is capable of communicating with a terrestrial cellular telephone communications system, it would typically be less expensive to transmit the uplink signals to terrestrial nodes than to transmit the uplink signals to a second satellite transceiver. However, where the computer user is too distant from a terrestrial cellular telephone system to operate effectively, the computer user, automatically or based on manual instructions, transmits uplink signals to the orbiting satellite system. Of course, even where the computer user is in range and transmits uplink signals to a terrestrial node, it is an object of the present invention that the downlink signals still be relayed by the satellite system to the user""s computer as typical terrestrial cellular telephone systems operate at transmission rates too slow to be practical for most computer users.
Other aspects and advantages of the invention will become apparent from the following detailed description and the accompanying drawings illustrating by way of example the features of the present invention.